Programmable Read-Only Memory (Prom): Installation

1. Ensure new PROM has same service number as old one or correct factory upgrade. Place NEW PROM in PROM carrier, and position squarely over PCM PROM socket. Press on PROM carrier until PROM is firmly seated in PCM.
   NOTE: Ensure reference notches in PCM and PROM are properly aligned. If PROM is installed backwards and ignition is turned on, PROM will be destroyed.
2. Install PROM access cover on PCM. Install PCM in vehicle. See INSTALLATION under CONTROL MODULE . Turn ignition on and ground DLC terminal "B". Check for DTC 51.
3. If DTC 51 is present, PROM is not fully seated in PCM, installed backwards, has bent pins, or is defective. If bent pins are cracked while straightening, replace PROM. If PROM is installed backwards or is defective, replace PROM.

Fig 1: Locating PROM On PCM

Courtesy of GENERAL MOTORS CORP.